Banks’ comments are a reference to the £11 million spent by former Prime Minister David Cameron during the campaign, setting out the reasons why economists, businesses, unions and politicians thought it was in the interests of the UK to remain part of the EU.

Leave.EU did not win the designation as the official Brexit campaign but was still a significant presence during the Referendum.

‘This followed an assessment which concluded that there were reasonable grounds to suspect that potential offences under the law may have occurred.

‘The investigation is focused on whether one or more donations – including of services – accepted by Leave.EU was impermissible; and whether Leave.EU’s spending return was complete.

Banks is a close friend of Ukip’s Nigel Farage (Picture: Getty)

‘The time taken to complete an investigation varies on a case-by-case basis. Once the investigation is complete, the Commission will decide whether any breaches have occurred and, if so, what further action may be appropriate, in line with its Enforcement Policy.

‘The outcome of concluded cases can be seen on the Commission’s website.’